1. Field of the Invention
The present invention relates generally to wireless communications and more particularly to systems and methods for cell-based wireless communications.
2. Description of Related Art
Many wireless systems require techniques allowing a base station to broadcast control messages to one or more users in an unsolicited fashion. The messages must often be sent in the presence of co-channel interference from other base stations. The requirement is driven in part by the increased user density and lower reuse factors enabled by interference cancellation techniques such as spatial filtering and adaptive beam-forming. These techniques are in turn enabled by modern standards such as IEEE 802.16 (WiMAX). Furthermore many of the newer standards have adopted orthogonal frequency-division multiplexing (OFDM) technology, which provide unique challenges and opportunities to equipment manufacturers.
Issues include co-channel interference (CCI) that limit performance, especially at the cell edge. For WiMAX, as the performance of the frame control header (FCH) and the media access protocol (MAP) deteriorate, so does system reliability. The only conventional approach to resolving this issue is provided in the WiMAX standard and involves increasing code repetition times and frequency reuse. However, this approach causes a large control channel overhead, and the efficiency of the control channel becomes very poor.